Post and corePrepared by :Mustafa moniem
Bahoz Himdad. Ari Aso
Supervised by :Dr. hisham
Post DiameterThe diameter of the post is dictated by the root canal anatomy.
A minimal dentin thickness of 1 mm around the post should be provided.
The width of the post should not be greater than one third of the width of the root at any point along the dowel.
Smaller posts not only conserve tooth structure, but also provide increased resistance to fracture compared with larger posts.
(A) too narrow (B) optimum size post (C) too largePost Design
Posts can be serrated, smooth, roughened or threaded.
Parallel, serrated posts are cemented into the canal passively. They are retentive and produce less stress in the root dentin than threaded systems
The Ferrule EffectThe ferrule is the circumferential ring of sound tooth structure that is enveloped by the cervical portion of the crown restoration.
A minimum sound dentine height of 1.5-2 mm is required between the core and crown margins.
This should provide adequate resistance to the lateral forces imparted on the restored tooth.
Ideally, this ferrule should be continuous around the entire circumference of the tooth.
The Ferrule EffectThe ferrule provides bracing or casing action to protect the integrity of the root.
Requirements of An Ideal Post• Minimum preparation.
• Resistance to fatigue.
• Elastic modulus similar to dentin.
• Non corrosive.
• Retentive (post & Head).
• Easy to adjust and fit.
• Adequate material
• Easy Removal
Types of PostsPrefabricated Post
Cast Post(wax pattern needed)
Cast post direct waxing
Indirect impression technique
• Preservation of maximum tooth structure
• Provision of anti-rotational properties
• Core retention
• Less chances of vertical fractures during preparation
• High strength
• Time consuming
• complex procedure
• Elliptical canals
• Flared canals
Prefabricated Tapered PostsAdvantages:
• Conserves tooth structure
• High strength and stiffness
Disadvantages:• Low retention
• Longitudinal splitting of remaining root
Indications:• Small circular canals
• Very tapered canals
Prefabricated Threaded PostsAdvantage
Disadvantages• Stresses generated in canal may lead to fracture
• Does not conserve coronal and radicular tooth structure
IndicationOnly when maximum retention is essential
Fiber Reinforced PostAdvantage
Indication• when there is sufficient tooth structure
• when there is no high occlusal loads
CORE partMaterials Used For Core Build Up
• Glass ionomer type II
• Good compressive strength
• Easy to manipulate
• Rapid polymerization
• Dentin bonding
• Polymerization shrinkage
• Poor dimensional stability
• Water sorption
• Technique sensitive
• Air bubbles and spaces
Excellent build-up material for posterior and anterior teeth if isolation assured
• Reduced marginal leakage
• Better dimensional stability
• Better compressive strength
• Better modulus of elasticity
Disadvantages• Mercury sensitivity
• Low tensile strength
• Corrosion with base metal
Molars with adequate coronal tooth structure
Glass Ionomer CoreAdvantages
• Easy to manipulate
Disadvantages• Low resistance to fracture
• Low retention to preformed post
• Sensitive to moisture
IndicationTeeth with minimum tooth structure missing
Gingival management• Retraction cord
• Rubber dam